`exportFrom` documentation misfeature

@DanGrayson is already working on this.

Since May 5, 2022.

Don't try to document functions exported from other packages. It can cause problems.

```m2
$ cat Goo.m2
newPackage ( "Goo", Headline => "goo" )

exportFrom_Core {"sin"}
$ M2
Macaulay2, version 1.19.1
with packages: ConwayPolynomials, Elimination, IntegralClosure, InverseSystems, LLLBases, MinimalPrimes, PrimaryDecomposition, ReesAlgebra, Saturation, TangentCone

i1 : installPackage ("Goo", Verbose=>true)
-- installing package Goo in /Users/dan/Library/Application Support/Macaulay2/local/ with layout #1
-- using package sources found in ./
-- storing raw documentation in /Users/dan/Library/Application Support/Macaulay2/local/lib/Macaulay2/Goo/cache/rawdocumentation-dcba-8.db
-- closed the database
-- running tests that are functions
-- making example result files in /Users/dan/Library/Application Support/Macaulay2/local/share/doc/Macaulay2/Goo/example-output/
-- processing documentation nodes...
-- processing Goo :: sin
-- processing Goo :: Goo
-- assembling table of contents
-- warning: found 1 documentation node(s) not listed as a subnode
-- making info file /Users/dan/Library/Application Support/Macaulay2/local/share/info/Goo.info
-- making html pages in /Users/dan/Library/Application Support/Macaulay2/local/share/doc/Macaulay2/Goo/html/
-- html page exists: /Users/dan/Library/Application Support/Macaulay2/local/share/doc/Macaulay2/Goo/html/index.html
-- html page exists: /Users/dan/Library/Application Support/Macaulay2/local/share/doc/Macaulay2/Goo/html/master.html
-- html page exists: /Users/dan/Library/Application Support/Macaulay2/local/share/doc/Macaulay2/Goo/html/toc.html
-- making html page for Goo :: sin
-- warning: missing node: Goo cited by sin
-- making html page for Goo :: Goo
-- making "Goo : Index" in /Users/dan/Library/Application Support/Macaulay2/local/share/doc/Macaulay2/Goo/html/master.html
-- making "Goo : Table of Contents" in /Users/dan/Library/Application Support/Macaulay2/local/share/doc/Macaulay2/Goo/html/toc.html
-- not making documentation in PDF format
-- warning: 1 warning(s) occurred in documentation for package Goo
-- file created: /Users/dan/Library/Application Support/Macaulay2/local/lib/Macaulay2/Goo/.installed
-- installed package Goo in /Users/dan/Library/Application Support/Macaulay2/local/

o1 = Goo

o1 : Package
```